One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,17)(12,20)(13,15)(14,18)(16,22)(19,23)(21,24)(25,26)(27,38)(28,34)(29,40)(30,37)(31,36)(32,35)(33,39) involution — undirected(2,5)(3,7)(9,11)(10,14)(12,21)(13,18)(15,17)(16,24)(19,22)(20,23)(25,27)(26,33)(28,32)(29,30)(31,39)(34,37)(35,40)(36,38) involution — undirected(11,18)(14,17)(19,21)(23,24)(25,28,31,29)(26,33,36,38)(27,30,39,32)(34,37,40,35)(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,20)(23,24)(25,29,31,28)(26,34,36,40)(27,30,39,32)(33,37,38,35)(2,5)(6,8)(9,12,13,22)(10,16,15,20)(11,19,18,21)(14,23,17,24)(25,30,31,32)(26,35,36,37)(27,28,39,29)(33,34,38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.